Lecture 24: Magnetism

A set of vocabulary flashcards covering the fundamental concepts of magnetism, types of magnets, electromagnetism, and the Earth's magnetic field as discussed in Lecture 24.

Magnetism

The properties of magnetic objects, which are capable of attracting and repelling other magnets.

Electron spin

The motion of electrons orbiting a nucleus that generates magnetism.

Permanent magnet

A substance where all or most of the atoms contain the same spin alignment.

Magnetic domains

Regions of uniform magnetism within a material that can be thought of as tiny permanent magnets.

Gadolinium

A metal that acts as a permanent magnet at temperatures less than about $20\,^{\circ}\text{C}$.

Magnetic field

The influence that a magnet has on other magnets and charged particles.

Field line convention

The principle that, outside of a magnet, field lines point from north to south, and inside they point from south to north.

Iron filings

Magnetic materials that align themselves along magnetic field lines, used to visualize the influence of a magnet.

Compass

A magnet suspended in a fluid that is free to rotate and aligns itself with the strongest magnetic field in the vicinity.

Repulsion

The force experienced when two like magnetic poles, such as north and north or south and south, are held together.

Attraction

The force experienced when two unlike magnetic poles, north and south, are held near each other.

Iron-oxide ceramics

Materials frequently used to create low-cost permanent magnets.

Rare-earth metals

Elements used to create very strong and small permanent magnets, often shaped into disk magnets.

Bar magnet

A long rectangular magnet with a north pole at one end and a south pole at the other end.

Horseshoe magnet

A bar magnet bent into a U-shape, bringing the north and south poles closer together.

Disk magnet

A short cylindrical magnet with poles located at the top and bottom.

Ferrofluid

A liquid containing tiny suspended magnetic particles that can be attracted to a magnet.

Electromagnet

A device where a magnetic field is created by current flowing through a wire, which can be turned on and off.

Iron core

A material placed in the center of a coiled wire to increase the magnetic field strength of an electromagnet.

Deflecting force

A force experienced by a moving electric charge that acts perpendicular to both the direction of current flow and the magnetic field.

Right-hand rule

A method using the index finger (current), middle finger (magnetic field), and thumb (deflecting force) to determine the direction of deflection.

DC motor

An application of the magnetic deflection force that uses a battery, a coil of wire, and a magnet to create mechanical work.

Centripetal force

A force that causes objects to move in a circular path, which in particle accelerators is provided by the magnetic deflecting force.

Advanced Photon Source

A particle accelerator located at Argonne National Lab in Lemont, Illinois.

Large Hadron Collider

The world’s largest particle accelerator, located in France and Switzerland.

Earth's magnetic field

A field generated by currents of molten iron and nickel in the planet's core that allows for navigation and protection from solar winds.

Solar wind

Charged particles emitted from the sun that would cause the Earth’s ozone layer to disintegrate without magnetic protection.

Aurora

Spectacular light displays generated when the Earth's magnetic field deflects the solar wind.